Outer Limits 4x4 Board

hey all asking a question for a mate. He engages diff lock at the transfer case but it doesnt work as both tires are not driving.

Can anyone point out any likely causes for this and what is needed to rectify the problem.

Thanks in advance.

It locks the centre diff in the transfer case. Not the front or rear diffs.

thanks but what does locking the transfer case do? what are the benifits?

Sorry for the noob questions.

In a Disco or most Landrovers actually. They are constant 4WD so you can not select 2WD. If they do not have a centre diff they get transfer case wind up(try driving your zook in a couple of circles while in 4WD on Concrete and see what happens as it doesnt have a centre diff) Now obviously it needs to be an open diff to stop this wind up as the front diff centre turns at a different speed to the rear durring turns. But if you leave the centre diff open offroad you will end up stuck spinning either one front or rear wheel. So locking the centre diff effectivly locks both tailshafts together so you get equal drive front to rear.

ok thanks for the explanation.